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Palaeogeographical maps showing the distribution of the palaeotropical coal forests during three times in the Carboniferous Period. Light grey – lowland areas; dark grey – upland areas; black – areas of palaeotropical coal forest.
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The palaeobotanical record associated with the coal-bearing sequences of Euramerica has historically been
taken to epitomise Pennsylvanian (late Carboniferous) vegetation. However, both the macrofloral and the palynological record reveals a much more complex picture of low-latitude vegetational habitats of this age. Many of these other vegetation t...
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... They are the foliage of a taxonomically coherent ("natural") group of plants but within which at least seven distinct fossil-species can be recognised, each with its own geographical and stratigraphical range. The group of plants originated in the upland intramontane coal swamps of the Variscan Mountains during Duckmantian times and then during the Bolsovian invaded lowland paralic areas of the Variscan Foreland, as part of a major reconfiguration of the coal swamp vegetation also seen with the medullosalean pteridosperms and herbaceous lycopsids (Thomas, 1997;Falcon-Lang, 2004;Thomas & Cleal, 2017;Cleal & Cascales-Miñana, 2019;Šimůnek & Cleal, 2020). This was part of a major reconfiguration of the coal swamp biotas known as the Morganian-Ammanian transition in the middle Bolsovian (e.g., Trueman, 1946) and coincided with global climatic cooling (the onset of the Late Palaeozoic Ice Age Glaciation Phase C4- Fielding et al., 2008Fielding et al., , 2023 causing a drop in sea levels and so less-frequent marine flooding of the paralic basins, and enhanced substrate drainage as the Central Pangaean Mountains expanded northwards (e.g., ...
Seven fossil–species can be distinguished within the range of late Carboniferous and early Permian equisetopsid (“horsetail”) foliage formerly assigned to Annularia stellata. The shoots bearing this foliage also produced distinctive strobili often known as Calamostachys tuberculata. These foliage species can be differentiated by leaf and whorl morphology, and each species has a distinct geographical and stratigraphical range. The group first appeared in the intramontane basins of the Variscan Mountains in the late Duckmantian, and then expanded into the lowland paralic coal swamps in the Bolsovian–Asturian. The group continued to flourish in coal swamp refugia during the Stephanian but eventually disappeared during the early Permian.
... Further work is clearly needed on the detailed dynamics of the different macrofloral fossil-species in order to determine exactly how the various plant species of the coal swamp vegetation were responding to these ecological pressures. It will also be important to investigate further the relationship between the macrofloras of the lowland paralic basins such as Nord-Pas-de-Calais and of the upland intramontane basins such as Saar-Lorraine and the Bohemia Massif, as this relationship seems to have played a key role in the overall evolution of the coal swamp vegetation during Westphalian times (e.g., see discussion in Thomas and Cleal, 2017;Cleal and Cascales-Miñ ana, 2019;Š imůnek and Cleal, 2020). Nevertheless, the new data presented here seem to confirm other studies in Europe (e.g., Cleal et al., 2009Cleal et al., , 2011) that climate change was at most only a subsidiary factor in the collapse of the coal swamp biome. ...
During recent years, different studies have focused on characterising plant diversities in the Carboniferous environments of the Variscan Foreland. One of these areas, the Nord-Pas-de-Calais Coalfield, has a Namurian–Westphalian sequence that has historically yielded abundant evidence of vegetation change, but to date, little attention has been paid to its macrofloral diversity dynamics. Here we show, for the first time, a comprehensive characterisation of the diversity changes and macroevolutionary patterns from this coalfield. The results show evidence of low levels of species richness during the Namurian, followed by an exponential diversification at the base of Westphalian. Duckmantian–Bolsovian species diversity continues to progressively increase, suggesting relatively stable conditions at that time. Maximum species richness is observed at the mid-Bolsovian followed by a major depletion during the Asturian. Overall, this pattern is quite similar to that seen in other parts of the Variscan Foreland. However, we see Nord-Pas-de-Calais vegetation diversified earlier than those in the British parts, probably because the dynamics of marine incursions and lacustrine conditions delayed its development in the latter areas. Furthermore, we also see the Asturian decline of the Nord-Pas-de-Calais coal swamp occurred later than in other basins, such as in the Pennines, Ruhr, and South Wales. This scenario suggests that the collapse of this biome was probably caused by increased sediment influx and reduced subsidence, resulting from the northwards migration of the Variscan Mountains. This further supports other studies in Europe advocating that climate change was at most only a subsidiary factor in the collapse of the Pennsylvanian coal swamp biomes
... We are inclined to ascribe the co-occurrence of Stephanian and Westphalian elements as caused by the small dimensions of the Zwickau and Lugau-Oelsnitz subbasins surrounded by extrabasinal areas or hinterland prone to erosion [99]. However, we assume the possibility of a much more internally structured intramontanous basin [100]. As such, the varying substrate could have favored vegetation types that thrived under confined-space different hydrological and edaphic conditions ranging from peat mires and clastic-substrate wetlands to slightly elevated ones occasionally-dry areas adjacent to the coal swamps. ...
Large-winged blattoids of the Middle to Late Pennsylvanian reveal a striking appearance, diversification, and decline in the fossil record. Among them, the families Necymylacridae Durden, 1969, and Gyroblattidae Durden, 1969, as well as the mylacrid genus Opsiomylacris exhibit, the largest pre-Cenozoic blattoids with forewing lengths up to 7.5 cm. As finds from coal-bearing sedimentary basins in Europe, North Africa, and North America indicate, these giant insects started to spread around the Bashkirian–Moscovian transition and experienced a diversification in late Moscovian and Kasimovian times, until they disappeared in the middle Gzhelian. Whereas necymylacrids are only patchily reported and still lack distributional patterns, we disclose the occurrence and particular habitat preference of gyroblattids. Although appearing first in some vast North American basins,
they became successively widespread only in small-sized basins of the European Variscan interior. Frequently found associated with enigmatic gymnosperms, they may have lived in well-drained hinterland areas from where they immigrated into the ever-wet basin centers only with increasing seasonality. Gyroblattids apparently followed meso- to xerophilous plants and likely colonized spaces offering a broader spectrum of edaphic conditions that resulted from the closeness of erosional and
depositional areas. The presented analysis and revision of all gyroblattids aim to facilitate future more realistic biodiversity estimations based on fossil taxa.
... However, since there is no evidence of taxa such as Adiantites, Pseudadiantites and Rhacopteridium that have been interpreted as allochthonous remains of hinterland vegetation (e.g. Wagner 2001), it is likely that this macroflora was derived from vegetation growing in well-drained alluvial habitats within the basin (see discussion by Thomas and Cleal 2017). ...
The “Coteaux du Pont Barré” in Beaulieu-sur-Layon is a Regional Natural Reserve which is home to exceptional flora and fauna. Recently fossil plants have been discovered at the site adding to its natural heritage significance. The exposure which is part of the “Sillon Houiller de la Basse- Loire” contains Serpukhovian-age (330–320 Ma) remains of sphenophytes, ferns, and lyginop- teridopsid and cycadopsid pteridosperms, which are described for the first time as well as the geology of the site. Most Carboniferous macroflora previously described from the Maine-et- Loire has been based on ex situ specimens from now abandoned and inaccessible coal mines. The newly described macroflora shows evidence of in situ remains and differs somewhat in composition from those reported from the coal workings, especially in the total absence of lycopsids and Calymmotheca pteridosperms, and instead having abundant medullosalean foliage (Neuralethopteris). The co-occurrence of Sphenopteris elegans and Neuralethopteris densifolia suggests a slightly younger age compared to the macrofloras documented from the coal-bearing deposits. However, this could be an ecological consequence of the flora growing in better-drained substrate habitats.
... The conditions that controlled the Late Paleozoic plant distribution especially in the tropics is still under debate. For instance, Kerp (1996); Thomas (1999, 2005) and Thomas and Cleal (2017) highlighted that in paleotropical areas the climate was permanently humid and proposed that topography and clastic inputs were the main mechanisms that controlled the formation of stagnant water and, as a consequence, the distribution of plants in wetlands. An alternative hypothesis considers that the main driving force of the vegetation was the climate because in some areas, like in the Bohemian Massif, floral changes do not match the tectonic events, which are considered to enhance clastic inputs and the topography (Opluštil et al., 2017). ...
The Pennsylvanian flora from the intramontane Erillcastell Basin in the eastern Pyrenees (Catalonia, Spain) is described in a palaeoenvironmental context based on a combined study of sedimentology, plant taphonomy and paleoecology. This basin differs from other Pyrenean basins of this age in comprising a wide array of fluvial channel and floodplain-related facies, with a limited development of peat mire facies. Both late Moscovian and early Ghzelian successions are rich in diverse calamitalean remains (mainly Calamites cistii and C. suckowii, in addition to C. undulatus in the Moscovian) and pecopterid foliage (mainly Polymorphopteris polymorpha) corresponding to marattialean tree ferns. An unusual feature of the fluvial channel assemblages is the common occurrence of arborescent lycopsids, especially Sigillaria brardii, in association with Calamites species, which presumably occupied riparian niches. Palaeotopographic, drainage and climatic constraints of the Erillcastell Basin may explain this unusual ecological distribution of Sigillaria brardii, which is mostly associated with peat mires and oxbow lakes in other coeval intramontane South European basins. Findings improve knowledge of intermontane forest ecosystems during the Middle to Late Pennsylvanian transition.
... To some extent, the gymnosperm-dominated LWD taphocoenoses are mirrored by plant assemblages found in the intercalated floodplain red beds. The latter deposits typically provide meso-to xerophilous impression floras historically referred to as ''upland elements'' but nowadays considered dryland associations (Thomas and Cleal 2017;Bashforth et al. 2021). These taphocoenoses include leaves, shoots, branches, fronds, seeds, and stem impressions of cordaitaleans, walchian conifers, callipterid and medullosan pteridosperms, calamitaleans, and ferns in variable but often gymnosperm-accented compositions (Schriel 1922;Boersma 1973;Kerp et al. 2007;Cleal 2008;Boyarina 2010;Opluštil 2013;Opluštil et al. 2017;Trümper et al. 2020b). ...
By colonizing drylands, plants fundamentally changed continental deposition and, thus, intensified the interaction between life and sediments. Fossil large woody debris in epiclastic strata is a key archive of this environmental turnover, although its interpretation remains challenging due to taphonomic biases. We review voluminous fluvial red-bed successions with sizeable silicified trunks that characterize Middle Pennsylvanian–lower Permian strata of east-central Europe. The stratigraphic occurrence, petrography, architecture of the deposits, and the preservation and nature of the fossil wood are discussed in the context of the tectono-climatic and vegetational evolution of the central-Pangean low latitudes. The log-bearing successions are assigned to five distinct, regionally traceable stratigraphic levels between the middle Moscovian and early Asselian. Up to 20 m long, mostly decorticated trunk fragments occur isolated in more or less feldspathic channel deposits, the architectures and dimensions of which point to large-scale river systems with highly variable discharge. Wood anatomy and floodplain adpression-fossils show that the trunks were derived from cordaitaleans, conifers, and arborescent sphenopsids in more diverse, gymnosperm-dominated dryland floras. The fossil record is biased towards successions formed in large-catchment river systems and, thus, does not accurately document the genuine nature of plant-distribution patterns. Rather, the strata show that large woody debris preservation depended on fluvial style and hydrological regime, hence turning the woody deposits into climate archives. The strata elucidate the climate development in equatorial Pangea, paralleling the acme of the Late Paleozoic Ice Age.
... It has been suggested that marine diversity patterns through time have been controlled by tectonics and changing sea-levelthe so-called 'common-cause' (CC) hypothesis (Peters, 2005;Smith and McGowan, 2011;Smith and Benson, 2013;Zaffos et al., 2017;Close et al., 2018). Analogous cycles of transgression and regressions may also have affected the diversity observed in the plant fossil record, which is naturally skewed towards lowland rather than upland vegetation: uplands are generally erosional, and not depositional environments (Thomas and Cleal, 2017;Cleal and Cascales-Miñana, 2019), and there are no unequivocal examples of preserved in situ upland vegetation until the Carboniferous, and are in fact generally rare throughout the Phanerozoic (Falcon-Lang, 2003;Boyce and Lee, 2017). ...
During the mid-Palaeozoic, vascular land plants (i.e., tracheophytes) underwent a great radiation that triggered the development of the land biosphere – the so-called Silurian–Devonian terrestrial revolution. However, little is known about how different plant groups impacted this process. A newly constructed dataset of plant macrofossil genera is used to characterize the tempo and mode of development of Silurian–Devonian vegetation and how it spread out over subaerial habitats. Important fluctuations of diversity and evolutionary rates of vegetation are linked to the diversity dynamics of particular tracheophyte groups. Despite a general increase of taxonomic richness through the Devonian, there was a clear stepwise pattern of origination and extinction events that resulted in the main floral transitions over time, such as the change to a forested landscape. To test if sampling bias may be affecting the observed diversity patterns, the latter were compared with the number of plant macrofossil localities as a proxy for sampling effort. This suggested a highly significant correlation between observed diversity and sampling effort, but it was not homogeneous, suggesting that at least some diversity fluctuations have a potential biological explanation. The sampling-corrected pattern of standing diversity suggests a clear increase of plant richness in the Pragian (Early Devonian) and Givetian (Middle Devonian), which may be related to the early expansion of the tracheophyte clades and the initial diversification of forested ecosystems, respectively. Further works should be focused on elucidate the impact of rock record on our understanding of Devonian plant diversification.
... All of the specimens described in this paper originated from Stephanian-age deposits of the Central and Western Bohemian and the Lugicau regions of the Bohemian Massif, Czech Republic ( Fig. 1). They represent upland wetland habitats (sensu Thomas and Cleal, 2017; see also Cleal and Cascales-Miñana, 2019) in an intra-montane basin complex formed within the Variscan Orogen (Pešek, 1994;Pešek et al., 1998;Opluštil et al., 2013b;Pešek and Sivek, 2016). The elevation of this basin complex in Westphalian times is estimated to have been ca. ...
Stephanian fronds from intra-montane basins of the Bohemian Massif in central Europe, previously named Neuropteris nervosa Šetlík, have been transferred to the fossil-genus Laveineopteris. This makes it the youngest known species of that genus. Current evidence suggests that they were more closely related to the Laveineopteris rarinervis fronds from the late Westphalian / earliest Stephanian lowland floras, rather than to Laveineopteris bohemica from the middle Westphalian intra-montane basin floras.
... As such they represent natural sampling of the vegetation from the volcanic slope. It cannot be said what transport distance or initial elevation the lahars at the foot of the KVC represent, but at least 300 m above sea level as required by Cleal and Thomas (2017) for a true upland flora is a reasonable assumption following the above arguments. ...
... The conditions that controlled the Late Paleozoic plant distribution especially in the tropics is still under debate. For instance, Kerp (1996); Thomas (1999, 2005) and Thomas and Cleal (2017) highlighted that in paleotropical areas the climate was permanently humid and proposed that topography and clastic inputs were the main mechanisms that controlled the formation of stagnant water and, as a consequence, the distribution of plants in wetlands. An alternative hypothesis considers that the main driving force of the vegetation was the climate because in some areas, like in the Bohemian Massif, floral changes do not match the tectonic events, which are considered to enhance clastic inputs and the topography (Opluštil et al., 2017). ...
